There is a conventionally proposed principle of a compressing mechanism which includes a rotary cylinder having a groove, and a piston slidable within the groove, so that the rotary cylinder is rotated in accordance with the movement of the piston to perform suction and compression strokes (for example, see German Patent No.863,751 and British Patent No.430,830).
The conventionally proposed principle of the compressing mechanism will be described below with reference to FIG. 8.
The compressing mechanism is comprised of a rotary cylinder 101 having a groove 100, and a piston 102 which is slidable within the groove 100. The rotary cylinder 101 is provided for rotation about a point A, and the piston 102 is rotated about a point B.
The movements of the piston and the cylinder will be described as for a case where the rotational radius of the piston 102 is equal to the distance between the rotational center A of the rotary cylinder 101 and the orbital center B of the piston 102.
When the rotational radius of the piston 102 is larger or smaller than the distance between the rotational center A of the rotary cylinder 101 and the orbital center B of the piston 102, different movements are performed. The description of these different movements is omitted herein.
A broken line C in FIG. 8 indicate a locus for the piston 102.
FIGS. 8a to 8i show states in which the piston 102 has been rotated through every 90 degree.
First, the movement of the piston 102 will be described below. FIG. 8a shows the state in which the piston lies immediately above the orbital center B. FIG. 8b shows the state in which the piston 102 has been rotated through 90 degree in a counterclockwise direction from the state shown in FIG. 8a. FIG. 8c shows the state in which the piston 102 has been rotated through 180 degree in the counterclockwise direction from the state shown in FIG. 8a. FIG. 8d shows the state in which the piston 102 has been further rotated through 270 degree in the counterclockwise direction from the state shown in FIG. 8a. FIG. 8e shows the state in which the piston 102 has been rotated through 360 degree in the counterclockwise direction from the state shown in FIG. 8a and has been returned to the state shown in FIG. 8a.
The movement of the rotary cylinder 101 will be described below. In the state shown in FIG. 8a, the rotary cylinder 101 is located, so that the groove 100 is located vertically. When the piston 102 is moved through 90 degree in the counterclockwise direction from this state, the rotary cylinder 101 is rotated through 45 degree in the counter-clockwise direction, as shown in FIG. 8b and hence, the groove is likewise brought into a state in which it is inclined at 45 degree. When the piston 102 is rotated through 180 degree in the counterclockwise direction from the state shown in FIG. 8a, the rotary cylinder 101 is rotated through 90 degree in the counterclockwise direction, as shown in FIG. 8c and hence, the groove 100 is likewise brought into a state in which it is inclined at 90 degree.
In this way, the rotary cylinder 101 is rotated in one direction with the rotation of the piston 102, but while the piston 102 is rotated through 360 degree, the rotary cylinder 101 is rotated through 180 degree.
The change in volume of the groove 100 defining the compressing space will be described below.
In the state shown in FIG. 8a, the piston 102 lies at one end in the groove 100 and hence, only one space 100 exists. This space 100 is called a first space 100a herein. In the state shown in FIG. 8b, the first space 100a is narrower, but a second space 100b is produced on the opposite side of the piston 102. In the state shown in FIG. 8c, the first space 100a is as small as half of the space in the state shown in FIG. 8a, but a second space 100b of the same size as the first space 100a is defined. This first space 100a is zero in volume in the state shown in FIG. 8e in which the piston 102 has been rotated through 360 degree.
In this way, the two spaces 100a and 100b are defined by the piston 102 and repeatedly varied in volume from the minimum to the maximum and from the maximum to the minimum, whenever the piston 102 is rotated through 360 degree.
Therefore, the spaces defining the compressing chambers perform the compression and suction strokes by the rotation of the piston 102 through 720 degree.
The above-described compressing principle suffers from the following problem: When the piston 102 is at the center A of rotation of the rotary cylinder 101, the direction of a force provided by the rotational force of the piston 102 is the same as the direction of the groove 100 and hence, this force does not rotate the rotary cylinder 101. Therefore, when the piston 102 is at the center A of rotation of the rotary cylinder 101, the above-described movement is actually continuously not performed, if the rotational force is not applied to the rotary cylinder 101.
Various methods for providing the rotational force to the rotary cylinder 101 against the above problem are considered currently, and it is an object of the present invention to provide an optimal approach in a hermetic compressor used in a refrigerating cycle system.
A continuous movement is realized by using two compressing mechanisms synchronized with each other with different phases. More specifically, by two compressing mechanisms synchronized with each other with different phases, the rotational force of one of the rotary cylinders can be applied to the other rotary cylinder. Therefore, even if either one of the rotary cylinders is brought into a state in which it does not receive the rotational force from the piston, the other rotary cylinder applies the rotational force to the one rotary cylinder and hence, the rotation can be continuously maintained. However, when the two compressing mechanisms synchronized with each other with different phases are used, two compressing chambers must be independent, because the compression strokes in the two compressing chambers are different from each other. Therefore, a partition plate is required between the rotary cylinders defining the two compressing chambers. On the other hand, a shaft for driving the piston in each of the compressing chambers is also required. Thereupon, a through-bore for passage of the shaft is required in the partition plate.
In this case, it is not preferable that the shaft is constructed with a dividing member connected thereto from a strength consideration and a accuracy consideration. Thus, a large compressing force is applied to the shaft for driving the piston, but a large torsional stress is applied to the shaft. With the above-described compressing mechanisms, not only the positioning relationship between the piston and the rotary cylinders but also the positioning relationship between the two rotary cylinders must be regulated with a good accuracy in an assembling step. Therefore, for example, if a construction is employed in which the shaft and the dividing member are fitted with each other in a screwing manner, it is difficult to ensure the accuracy.
From the above reason, the shaft is formed from a single member. However, if the shaft is formed from a single member, the shaft must be inserted from one side of the partition plate.
Accordingly, it is an object of the present invention to provide a construction of two compressing mechanisms interconnected in a synchronized manner and capable of being industrially produced, which construction is employed in a hermetic compressor.
It is another object of the present invention to provide a hermetic compressor having a higher compression efficiency by preventing the communication between compressing spaces having different phases.